Prevention and relaxation effects of Liriope platyphylla on bronchial asthma in vitro model by suppressing the activities of MAPK/NF-κB pathway

Backgrounds: Bronchial asthma (BA) is a common type of asthma, defined as a chronic inflammation, hyperplasia, and hypercontraction of the airway. In this study, we investigated whether Liriope platyphylla extract (LPP) can help prevent inflammation, suppress hyperplasia, and support relaxation via regulation of MAPK/NF-κB activity. Methods: To investigate the inflammation prevention effects, A549 cells, a human airway epithelial cell line, were pretreated with various concentration of LPP and then treated with EGF recombinant (10 ng/mL). Anti-hyperplasia and muscle relaxation experiments were performed with asthma condition human bronchial smooth muscle (hBSM) cells. The effects of LPP on MAPK/NF-κB activity and MAPK/NF-κB-related signaling, such as COX-2 and iNOS expression, was analyzed through western blot analysis. The mRNA expression levels of Th-2-cell-related cytokines, including IL-6 and TNF-α , and contraction-related factors, such as PLCβ, IP 3 R, and MLCK , were determined by real-time PCR. Results: LPP pretreatment significantly reduced MAPK/NF-κB activity in EGF-induced asthma condition A549 cells. Therefore, there was significant suppression of both COX-2 and iNOS expression. In addition, the mRNA expression of IL-6 and TNF-α was dose depen-dently reduced. Although there was no statistical significance, factors related to contraction showed a tendency to decrease. Conclusion: Based on our results, we believe that LPP shows good potential for application as a therapeutic agent for asthma through inflammation prevention and bronchial smooth muscle relaxation.